This Mac Plus boots off cold and after about ten minutes the screen goes dead, it used to be fine if I gave it a tap on the side of the housing but today it just refused to come back on unless I let it cool back down, then the cycle repeats. Removing the cover and bending the board back and tapping it in a few spots gets it back for a moment but then goes back to black. any ideas would be appreciated!
You can see the fault here:

All right, as embarrassing as it sounds I found the issue ... I was cleaning the memory chips and putting them back in when I found out that a resistor on the logic board been knocked out. A little bit [sic] of solder later and its fixed. Screen is grey again and everything boots properly.